tests/unit: Add an unit test for smp parsing

tests/unit: Add an unit test for smp parsing

Now that we have a generic parser smp_parse(), let's add an unit
test for the code. All possible valid/invalid SMP configurations
that the user can specify are covered.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20211026034659.22040-3-wangyanan55@huawei.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <bfed7144-af86-7098-e7a6-731ff13c2cf7@huawei.com>
[PMD: Squashed format string fixup from Yanan Wang]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>